Single line pressure-pressure pneumatic tube system

ABSTRACT

A single line, pressure-pressure, pneumatic tube system having a pair of terminals each being capable of dispatching or receiving carriers. Each terminal provided with a blower to provide air flow, tubing connecting the two terminals, a pair of inline valves in the tubing, one facing in one direction and the other in the opposite direction. The valves being so designed that the one near the dispatching terminal automatically closes to permit build up of pressure and the one near the receiving terminal opens to exhaust pressure and slow the travel of the carrier as it approaches the receiving terminal, the terminal having a bleed-off orifice to assure carrier arrival.

This application is a continuation of application Ser. No. 124,897,filed Feb. 26, 1980, now U.S. Pat. No. 4,325,660.

DESCRIPTION

1. Technical Field

This invention relates to an improved single line, pressure-pressure,pneumatic tube system having automatic means controlling the speed ofthe carrier.

2. Background Art

One of the difficulties of single line, pneumatic tube systems has beenthe speed of the carrier at the receiving terminal, particularly duringpressure operation. U.S. Pat. No. 4,189,261 discloses an improved singleline, pressure-vacuum pneumatic tube system with a relief valve remotefrom the end terminal that during pressure operation discharges the airpressure, whereby the end travel of the carrier is slowed. U.S. Pat. No.2,698,721 discloses a similar system. However, these two systems whilesingle line, operate on pressure in one direction and vacuum in theother. While there are several single line pneumatic tube systemsavailable in the United States which operate on pressure in bothdirections, as far as is known, none of the systems satisfactorilycontrol the speed of the carrier at the receiving terminal. Hence thecarrier arrives at the receiving terminal at a very high speed which isinjurious to the carrier. One means that has been used to slow the speedof the carrier is to time the blower so that it cuts off prior tocarrier arrival; however, this requires precise timing since if theblower does not operate sufficiently long, the carrier will get stuck inthe tubing. Another method is to exhaust the air in front of the carrierthrough the blower assembly in the receiving terminal, however, this isquite noisy and does not satisfactorily slow the carrier. This alsocreates a continuous back pressure that makes the overall operation ofthis system slower as well as it overworks the blower in the dispatchingterminal.

DISCLOSURE OF INVENTION

In accordance with the present invention, a single line,pressure-pressure pneumatic tube system is provided with a pair ofinline valves which are positioned in the horizontal run of tubing. Eachvalve is the same, however they are positioned in opposite directions sothey will automatically operate in the correct manner depending upondirection of travel of the carrier. Each valve has a pivoted valvemember. When there is no pressure in the system, the valve member hangsin the air stream, due to gravity, and the valve is full open. When thedispatching terminal is pressurized, air in front of the carrier causesthe valve member, near the dispatching terminal to move toward a closedposition. Within one carrier length after passage of the carrier,through the valve near the dispatching terminal, the valve will move tothe full closed position, thereby maintaining pressure in the tubing,the transmission line, and providing for movement of the carrier.Meanwhile the valve, near the receiving terminal, is open and,accordingly, air in the tubing will be discharged and the speed of thecarrier will not be impeded by dead air or back pressure as a result ofpushing air thru a dead blower. As the carrier moves through the valve,near the receiving terminal, the valve will fully open and air in backof the carrier will be discharged lowering the pressure, whereby thepressure on back of the carrier will decrease, and the carrier will slowdown. Moreover, the carrier will compress the air in the tubing in frontof the carrier and further slow down the speed of the carrier. Carrierarrival at the receiving terminal will be soft as a result of thedecrease in pressure plus the arresting action of the compressed columnof air between the valve and the receiving terminal. A small bleed offorifice in the terminal relieves the air in front of the carrier so thatthe carrier will not be stopped in the tubing.

BRIEF DESCRIPTION OF DRAWINGS

The details of the invention will be described in connection with theaccompanying drawing, in which:

FIG. 1 is a diagrammatic view of the system of the present invention,illustrating the position of the valves with no pressure.

FIG. 2 is a diagrammatic view of the tubing in FIG. 1 after the carrierhas passed the valve nearest the dispatching terminal.

FIG. 3 is a view similar to FIG. 2 after the carrier has passed thevalve nearest the receiving terminal.

FIG. 4 is a cross section of the valve utilized to automaticallyregulate the speed of the carrier.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to the drawings, a single line, pressure-pressure pneumatictube system constructed in accordance with the present invention iscomprised of terminals 2 and 4, either one of which may act as adispatching terminal or a receiving terminal. Terminal 2 is shown infront plan and terminal 4 is shown in side elevation. The two terminalsare connected by tubing 6 which in normal installation will have twovertical runs and a horizontal run. A carrier 8 is transmitted from oneterminal to the other terminal through the tubing 6. To provide airpressure to drive the carrier, each terminal is provided with a smallelectric blower 10 controlled by an electronic timing circuit energizedby push button 12. The blower may be connected to any normal 110 V ACelectrical circuit through a conventional plug 14 attached to anelectrical cord. To provide quiet operation, the blower may be encasedin a housing 16, formed of sound deadening material, which may be alength of PVC tubing. The electronic timing circuit will determine theinterval motor 10 will run when the button 12 is energized. The timewill naturally depend upon the distance between the two terminals.

Each terminal has a chamber 18, into which the carrier may be placedthrough a door 20 which in closed position fully seals the chamber. Thechamber is in communication with the blower 10 and also with tubing 6through a guide assembly 22 by which the terminal is attached to thetubing. The guide assembly 22 has a pivoted hanger which may be movedinto position shown for carrier dispatch. The weight of the carrier willmaintain it in such position. However, at other times, it willautomatically move out of the line of carrier travel. Therefore, if acarrier is placed in chamber 18 and the blower energized by pushingbutton 12, air from the blower will flow into chamber 18 striking thecarrier and forcing it through guide assembly 22 and into tubing 6. Oneproblem with a pressure-pressure system is that the carrier will beunder pressure throughout its entire trip, and; accordingly will arriveat the receiving terminal with a high velocity.

To control the speed of the carrier, the present system is provided withinline valves 24-26, which are identical, but placed in the horizontalrun of tubing in facing relation. Each valve is so designed that itautomatically opens or closes depending on the flow of air through thevalve. The low pressure air preceding the carrier will set the mode ofthe valve and the higher pressure air trailing the carrier will completethe operation. When a carrier is put into motion, the valve nearest thedispatching terminal will start to close ahead of the carrier. As thecarrier passes through the valve, the higher pressure behind the carrierwill cause the valve to complete its seal. On the other hand the valvenearest the receiving terminal facing in the opposite direction willstart to open under the low pressure ahead of the carrier and evacuatewhat would be compressed air in front of the carrier. After the carrierpasses through the valve, the valve will move to a full open positionand exhaust all the air behind the carrier into the atmosphere. Sincethe valves are placed in the horizontal run of tubing, which is normallyabove the ceiling, any noise from the exhausting of air will beminimized. The carrier then enters a dead air column and starts todecelerate, compressing the air ahead of it until the carrier makes asoft landing in the receiving terminal. Since the braking action of thedead air column could bring the carrier to a stop before it arrives atthe receiving terminal, each chamber 18 is provided with at least onesmall bleed off port hole 28. To provide air for operation of thesystem, each terminal is provided with an intake valve 30 formed of afree hanging sheet of rubber reinforced with metal which may swing intochamber 18. Accordingly, when the blower in the dispatching terminal isstarted, valve 30 in the dispatching terminal opens to provide air. Atthe same time air arriving at the receiving terminal forces intake valve30 in the receiving terminal closed. To further cushion the arrival ofthe carrier, the bottom of each chamber may be provided with a pad of 32of shock absorbing material.

In order to accomplish the above defined operation automatically, valves24-26 have pivoted valve members 34, each carrying a seal 36. Thepivoted valve member may be formed of an arcuate strip of metal and dueto gravity, hangs in the path of the air stream. Low pressure air infront of the carrier will bias the valve member toward either open orclose depending on which face of the pivoted valve member the airstrikes.

FIG. 4 being a cross section of the valve discloses such construction aswell as the construction of the valve as a whole. As can be seen thevalve has a main body 38 which may be formed from a length of tubingwhich is the same diameter as the tubing and is connected into thehorizontal run of tubing 6. The body 38 has a longitudinal opening 40and mounted thereon is a housing 42 which may have slanting end walls44. The top of the housing 42 is provided with an exhaust port 46. Theexhaust port is so designed that the seal 34 will seal around it inclosed position. Mounted in the housing 42 adjacent the slanting endwalls 44 is rod 48 which acts as a pivot for pivoted valve member 34. Ascan be seen in FIG. 1, gravity causes the pivoted valve member 34 andseal 36 to extend slightly into the path of air flow in the tubing. Anyair movement in the tubing will cause the valve member 34 to swing toeither a partially closed or a partially open position depending on thedirection of flow. The higher pressure following the carrier will causethe valve to fully close or open. In the closed position, the seal 36will engage the exhaust port 46 and close the air flow. In the openposition, the valve member 34 will be away from the port 46 allowing airto be discharged. The valve will remain in such position until the airpressure drops to below that amount required to override the force ofgravity. At such time, the valve member will drop to a vertical freestanding position and be in position to automatically react to the nextmovement of air regardless of which direction it may come from. As canbe seen in FIG. 4, the slanting end wall of housing 42 extends pastlongitudinal opening 40 so that there is a ledge 50, the ledge 50 inconjunction with the pivoted valve member and seal cooperate to preventback pressure from improperly closing the valve by prohibiting air fromgetting in back of the valve member and seal.

Accordingly, assuming that terminal 2 is the dispatching terminal andterminal 4 is the receiving terminal, the carrier 8 is placed in thehanger of guide assembly 22 of terminal 2 and by pushing button 12, airflow in chamber 18 wil strike the carrier 8 and start its movementthrough tubing 6. The air in front of the carrier will strike theswinging valve member of valves 24-26 and will cause the valve membersto start moving toward their predetermined positions. In the valve 24nearest terminal 2, the valve member will move toward closed and in thevalve 26 nearest terminal 4, the valve member will move toward open. Ascarrier moves through valve 24, the high pressure air in back of thecarrier will move the valve member to a fully closed position within onecarrier length. i.e., the seal 36 will engage with the wall surroundingthe exhaust port to effect a seal. The valve member will remain in suchposition until the pressure in the tubing drops below the pressurecounteracting gravity forces acting on the valve member. Meanwhile valve26 near receiving terminal 4 facing in the opposite direction will haveits valve member move toward the open position. As previously mentioned,the ledge 50 will prevent back pressure from moving the valve toward aclosed position. Valve 26 will exhaust air in front of the carrier andaccordingly dead air will not impede transmission of the carrier. As thecarrier passes valve 26, the high pressure air in back of the carrierwill cause the valve member to remain open and air in back of thecarrier will be discharged into the atmosphere through exhaust port 46.As mentioned, the valve will usually be above the ceiling and noise fromexhausting air is minimized. Since the air in back is discharged, thepressure on the carrier is decreased. Also there is a dead air columnbetween the front of the carrier and receiving terminal 4. The carrierwill tend to compress the air and further slow the carrier. To assurethat the carrier reaches receiving terminal 4, orifice 28 slowlydischarges air. Therefore, the carrier makes a soft landing.

As can be seen for the foregoing, the pressure-pressure system of thepresent invention is provided with a pair of inline valves in facingrelation which automatically control the speed of the carrier so that itis automatically slowed as it approaches the receiving terminal andshock to the carrier is greatly reduced.

I claim:
 1. A single line pressure-pressure pneumatic tube systemcomprising: a first end terminal having a pressure unit therein; asecond end terminal having a pressure unit therein; a line of tubingconnecting the first terminal to the second terminal; two inline valvesin the tubing line, one adjacent each terminal; each of said valvescomprising a port for exhausting air from the tubing directly to theatmosphere and a freely pivotable closure means extending into thetubing and being pivoted away from the port by air flow in the tubing inone direction and being pivoted into engagement with the port to closethe port by air flow in the tubing in the opposite direction; a carrierfor travel in the tubing from one terminal to the other terminal uponpressurization of a terminal; said two valves being arranged inopposition so that the valve adjacent the pressurized terminal commencesclosure when the carrier is upstream thereof and fully closes afterpassage of the carrier, while the valve adjacent the other terminalcommences opening when the carrier is upstream thereof for exhaustingair from the tubing in front of the carrier directly to the atmosphereand fully opens after the passage of the carrier to exhaust air in thetubing behind the carrier directly to the atmosphere thereby reducingthe pressure propelling the carrier and slowing the travel of thecarrier to the other terminal.
 2. The pneumatic tube system specified inclaim 1 wherein the inline valves are normally open and are sopositioned that upon pressurization, the valve adjacent the pressurizedterminal closes while the valve adjacent the unpressurized terminalopens.
 3. The pneumatic tube system specified in claim 1 wherein eachterminal is provided with a valve that is biased closed but opens whenthe system is pressurized to provide air to the system.
 4. The pnuematictube system specified in claim 1 wherein each terminal is provided witha small bleed off orifice to permit air in front of the carrier to bereleased.
 5. The pneumatic tube system specified in claim 1 wherein eachinline valve is comprised of a valve body formed of a length of tubing,a longitudinal opening in the tubing, a housing positioned over theopening, said exhaust port being formed in the top of the housing, apivot member in the housing, said closure means comprising a valvemember pivoted on the pivot member, a seal member of the valve member,the valve member moving to an open position as air flows in onedirection and to a closed position where the seal member is inengagement with the exhaust port with air flow in the oppositedirection.
 6. The pneumatic tube system specified in claim 5 whereineach inline valve therein is further provided with a ledge whichcooperates with the valve member to prevent improper closure.
 7. Thepneumatic tube system specified in claim 6 wherein the valve member isformed of an arcuate strip of material.
 8. The pneumatic tube systemspecified in claim 1 wherein the line of tubing comprises a horizontalrun terminating at each end in a vertical run connected to the adjacentend terminal, said valves being located in said horizontal run.
 9. Thepneumatic tube system specified in claim 8 wherein the horizontal run isrelatively long as compared to the vertical runs.
 10. The pneumatic tubesystem specified in claim 1 wherein the ports are constructed andarranged to exhaust air from the tubing to the atmosphere withoutpassing through the power units.
 11. A valve for use in the tube in apressure-pressure pneumatic tube system which automatically moves whenair flow in the tube is in one direction to a closed position and whenair flow in the tube is in the opposite direction to an open position,said valve comprising a valve body formed of a length of tubing, alongitudinal opening in the tubing, a housing positioned over theopening, an exhaust port in the top of the housing, a pivot member inthe housing, a valve plate in the housing pivoted on the pivot memberand extending into the opening in the valve body, the valve plate beingpivoted away from the exhaust port by air flowing in one direction andimpinging on one side of the valve plate and being pivoted intoengagement with the exhaust port to close said port by air flowing inthe opposite direction and impinging on the opposite side of the valveplate.
 12. The valve specified in claim 11 in which the valve plate isformed of an arcuate strip of material and a flat seal on a face of saidstrip of material, and there is a ledge extending between the openingand a slanted side of the housing adjacent the pivot member which incooperation with the arcuate strip of material and flat seal preventsunwanted closure of the valve by excluding pressurized air from thespace between the valve and the slanted side when the valve is in anopen position.
 13. The valve specified in claim 11 wherein the valveplate has an arcuate portion.
 14. A single line pneumatic tube systemcomprising a first end terminal having a power unit therein, a secondend terminal having a power unit therein, a line of tubing connectingthe first terminal to the second terminal, two inline valves in thetubing line, one adjacent each terminal, said valves comprising portsfor exhausting air from the tubing directly to the atmosphere and meansresponsive to passage of the carrier through the tubing for opening andclosing the ports, a carrier for travel in the tubing from one terminalto the other terminal upon pressurization of a terminal, said two valvesbeing arranged in opposition so that the valve adjacent the pressurizedterminal is closed after passage of the carrier while the valve adjacentthe other terminal is open when the carrier is upstream thereof forexhausting air from tubing in front of the carrier directly to theatmosphere and remains open after passage of the carrier to reduce thepressure propelling the carrier thereby slowing the travel of thecarrier to the other terminal, wherein the valve adjacent thepressurized terminal commences closure when the carrier is upstreamthereof and fully closes after passage of the carrier while the valveadjacent the other terminal commences opening when the carrier isupstream thereof and fully opens after passage of the carrier.